1. Field of the Invention
The present disclosure relates to a power control apparatus, and more particularly, to a power control apparatus having top-own type hierarchical power control units, and a control method thereof.
2. Discussion of the Related Art
Minimal power consumption has become more an issue as electronic devices are smaller and more highly integrated. In particular, in the field of mobile communications system on chip (SOC), the reduction in the threshold voltage of a transistor through a refined process helps in the reduction of dynamic power. A method of maintaining minimum necessary information using multi threshold CMOS (MTCMOS) has been proposed in which, in the idle state, power is supplied only to blocks that need power while little or no power is supplied to blocks that do not need power.
FIG. 1 is a functional block diagram of a conventional power control apparatus using an MTCMOS. Referring to FIG. 1, a conventional power control apparatus 10 using an MTCMOS includes a power management unit 5 and a plurality of power domain blocks 6, 7, and 8.
Each of the power domain blocks 6-8 can be a set of hardware and/or modules divided by functions or operation modes. For example, for the mobile communications SOC, each set of functional modules can perform a multimedia function, a dual mode, a DMB function, or a DVB-H function can configure a different power domain block.
Each of the power domain blocks 6-8 can include at least one floating prevention circuit (FPC) 9. The structure and role of the FPC 9 is disclosed in detail in Korean Registration Patent Publication No. 10-054634 entitled “MTCMOS Circuit System having FPC” which is included herewith as a reference.
Also, the power management unit 5 includes a state machine 1 to control the MTCMOS controllers 2, 3, and 4. However, since the conventional power management unit 5 needs to control the power of the power domain blocks 6-8, the design of the power management unit 5 becomes complicated. Thus, there may need to be more area allocated to the power management unit and therefore, there may be more leakage current due to the power management unit itself.